Hello Penny -
What a beautiful place you have!
Sorry to hear about your situation, getting lower reviews because of the walk from the carport to the house.
I suggest this:
Spell the situation out.. clearly. Make it super clear, in your house description, maybe at the end, make a special note, like the following:
"PLEASE NOTE: The house is located on a hill. The parking for the home is in a carport below the house, and there is a incline to reach the front door of the house. The home may be difficult to access with those with mobility issues. Please feel free to ask any questions prior to booking".
I would also add in your pictures, a picture of the incline. That way potential guests could decide if the incline is an issue.
In addition, maybe take your home off "instant booking", that way you could inquire with potential guests if they understand there is incline from the carport to your home.
Or if you want to keep instant booking, after a guest book, sent them a message to make sure they understand the location of the house, and the incline.
Best,
John